[AIRFLOW-6789] BugFix: Fix Default Worker concurrency

[kaxil]

9b5dbf9#diff-bbf16e7665ac448883f2ceeb40db35cdR444 commit in airflow 1.10.8 (1.10.9) introduced a bug. It changed default worker concurrency

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Issue link: AIRFLOW-6789

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[kaxil]

This only exists in 1.10.8/1.10.9 (v1-10-* branches). Master does not have this bug

[codecov-io]

Codecov Report

Merging #7494 into v1-10-test will increase coverage by 0.37%.
The diff coverage is n/a.

@@              Coverage Diff               @@
##           v1-10-test    #7494      +/-   ##
==============================================
+ Coverage       80.96%   81.34%   +0.37%     
==============================================
  Files             529      529              
  Lines           36437    36437              
==============================================
+ Hits            29502    29640     +138     
+ Misses           6935     6797     -138

Impacted Files	Coverage Δ
airflow/utils/dag_processing.py	91.84% <0%> (-0.17%)	⬇️
airflow/bin/cli.py	66.91% <0%> (-0.11%)	⬇️
...etes_request_factory/kubernetes_request_factory.py	100% <0%> (+0.86%)	⬆️
airflow/contrib/kubernetes/pod.py	100% <0%> (+4.16%)	⬆️
airflow/contrib/kubernetes/refresh_config.py	74.5% <0%> (+23.52%)	⬆️
...rflow/contrib/operators/kubernetes_pod_operator.py	96.84% <0%> (+40%)	⬆️
airflow/contrib/kubernetes/pod_generator.py	87.5% <0%> (+45%)	⬆️
airflow/contrib/kubernetes/pod_launcher.py	92.48% <0%> (+47.36%)	⬆️
airflow/contrib/kubernetes/volume.py	100% <0%> (+50%)	⬆️
airflow/contrib/kubernetes/volume_mount.py	100% <0%> (+66.66%)	⬆️

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